Project Summary/Abstract Cancer is the leading cause of death for Latinos and Asian Americans, who are among the fastest growing populations in the U.S. A large proportion of Latinos and Asian Americans live in ethnic enclaves?distinct neighborhoods with high concentrations of individuals of the same ethnic origin (?co-ethnic residents?) that are also characterized by recent immigration and linguistic isolation. The existing literature is mixed, with some studies showing that ethnic enclave residence (vs. non-enclave residence) and foreign- (vs. U.S.-) birthplace are associated with both better and/or worse outcomes across the cancer continuum. In this study, we will pool cancer registry data across five states (CA, FL, NJ, NY, TX) comprising the majority of Latinos and Asian Americans in the U.S. and link these data to contextual data characterizing the social, built and healthcare environments. We will determine whether and how ethnic enclave residence and foreign-birthplace are associated with three cancer outcomes (incidence, stage at diagnosis, survival) experienced by nine of the largest Latino and Asian ethnic groups (Cuban, Mexican, Puerto Rican, Chinese, Filipino, Japanese, Korean, South Asian, Vietnamese) diagnosed with three cancer types (breast, cervical, and colorectal cancers). Specifically, we aim to define and characterize ethnic enclaves, and examine cancer incidence by enclave residence (Aim 1) and determine independent and joint associations of ethnic enclave residence and nativity (foreign vs. US birthplace) on stage at diagnosis (Aim 2) as well as on mortality (Aim 3). With over 200,000 Latino and Asian American breast, colorectal, and cervical cancer cases, we will use multilevel models to understand the impact of ethnic enclaves on cancer outcomes for these understudied populations. In doing so, our study will accelerate discovery about the intersections between neighborhoods, ethnicity, nativity, and cancer and will improve data and methods used by central cancer registries across the U.S. Findings have potential to inform development of multilevel interventions to leverage enclave attributes that promote health and to address any barriers to reduce disparities and improve outcomes for our fastest growing ethnic minority and immigrant communities. We will disseminate our enclave measure and imputation procedures for missing data to the North American Association of Central Cancer Registries (NAACCR). In doing so, our methods will improve completeness of cancer registry data for surveillance of the growing Latino and Asian American populations. Our dissemination plan with collaboration from NAACCR leadership as well as the Offices of Community Outreach and Engagement at NCI Designated Cancer Centers in five states will ensure 1) methods are readily adopted by cancer registries and health disparities researchers across the nation; and 2) findings inform community-engaged efforts to address multilevel cancer disparities among Latino and Asian populations.